I have had Prusa MINI for a few years already and I have printed PLA without an issue but recently I have printed only PETG for some time I got through multiple spools of PETG without any print in PLA. But after I tried to print PLA my extruder kept skipping and grinding filament and when I tried to feed filament by hand it went easy for a little bit but after that, it went very hard as if the filament was cold so I tried to bump up the temperature to 235C and it helped a little bit but on faster sections of print like the infill extruder is skipping again. I don't think I have unreasonable speeds i am using a standard Prusament PLA profile with Prusament PLA. I have also tried PLA+ from some different brand with the same result. Then I changed the nozzle from an E3D hardened steel nozzle with nano coating to brass (not new I have printed PETG on this one as well) still with the same result. PETG is printing fine. Is there something I can try, please? I am out of options.
You've got a jam. Filament is dried and burnt up in there. PETG is a lot more fluid / lower viscosity when hot, so it's flowing around the crusty. Take off nozzle, remove PET tube. You should have another PET tube in the spares bag that came with the printer. Clean out the extruder well.
I did have nozzle cleaned but my ptfe tube is totally melted and i lost the spare so i flipped it and it did helped a lot i have managed to print something without a fail but still only at high temperature 235C so i had a lot of strings so tomorow i will try to find the replacement i hope it will fix it